just blowing IN from all the vents/fans may or may not help since the gunk on the inside is not getting out. best thing to do is un-assemble the laptop so u can see the MB & fans then use compressed air to blow it clean. while it's open clean off & re-apply new thermal paste to the CPU.
note: if u have not un-assembled a laptop before I don't recommend it, the plastic pieces are easy to crack if u don't know what yer doing.